Joint osteoarthritis is a syndrome in which low-grade inflammation results in pain in the joints, caused by abnormal wearing of the cartilage that acts as a cushion inside if the joint. This abnormal wearing of the cartilage also results in a decrease of the joints lubricating fluid called synovial fluid. Joint osteoarthritis is estimated to affect 80% of all people over 65 years of age, in more or less serious forms.
The present treatment for joint osteoarthritis comprises NSAID drugs, local injections of hyaluronic acid or glucocorticoid to help lubricating the joint, and replacing part of the joint with a prosthesis through orthopedic surgery.
The replacing of parts of the joint is one of the most common surgeries to date performed at hundreds of thousands of patients in the world every year. The most common method comprises placing a metal prosthesis in Femur and a plastic bowl in acetabulum. This operation is usually done through a lateral incision in the hip and upper thigh and through, fascia lata and the lateral muscles of the thigh. To get access to the hip joint, the supporting hip joint capsule attached to femur and Ilium of pelvis needs to be penetrated, making it difficult to get a fully functional joint after the surgery. Femur is then cut at the neck with a bone saw and the prosthesis is placed in femur either with bone cement or without. Acetabulum is slightly enlarged using an acetabular reamer, and the plastic bowl is positioned using screws or bone cement.
The surgery typically requires one week of hospitalization due to the increased risk of infection. The recovery process is on average about 6 weeks, but even after this period the patient should not perform any physical activates that places large strain on the joint.
Conventional orthopedic surgery has drawbacks in that it is highly invasive, which damages the ligaments, tendons and surrounding tissue such that they are weakened. Some of the ligaments surrounding the joints, such as the ligaments of the hip and knee joint capsules never fully regain their strength once they are severed, resulting in the patient getting a limited motion range and/or load carrying capability. The large incisions are needed since the prosthetic parts usually are of considerable size and needs to be placed in contact with the joint through the incision. Making a large incision creates a large surface exposed to the threat of bacterial and/or viral infections and extends the needed hospital stay.